Inorganic salts of cellulose dicarboxylates and their preparation



Patented Sept. 21, 1937 UNITED "STATES PATENT OFFICE INORGANIC SALTS OF'CEIQLULOSE DICAR- BOXYLATES,AND THEIR PREPARATION Carl J. Malm,Rochester, N. Y., and Charles E. Waring, Dayton, Ohio, assignors, bymesne assignments, to Eastman Kodak Company,

. Jersey City, N. J., a corporation of New Jersey No Drawing.Application July so, 1932,-

Serial No. 62'l,149

22 Claims.

10 We have found that the cellulose acetate-dicarboxylates, such as acellulose acetate phthalate having an unesterified carb'oxyl group, maybe neutralized with an aqueous solution of an inorganic water-solublehydroxide to form a salt l5- of the cellulose acetate-dicarboxylate. Wehave found that the salts resulting from the treatment of a'celluloseacetate-dicarboxylate with an inorganic water-soluble hydroxide arewater soluble and may be coated out from their aqueous solutions to formsheets or.skins.

The preparation of the water-soluble salts of a celluloseacetate-dicarboxylate may be carried out" by adding a basic solution(su'chas of sodium, potassium or ammonium hydroxide) to asolution of theacetate-dicarboxylate dissolved in a liquid which is a good solvent forboth the cellulose acetate dicarboxylate and the salt to be formed,until neutrality is attained, and then the neutralized solution may bepoured intoa liquid which will '30 precipitate out the salt.

The preparation of these salts may instead be carried out in a liquidwhich is a solvent of both the dicarboxylic acid ester of cellulose andthe base employed in the reaction but which is a nonsolvent of the saltformed. In this case the salt precipitates out upon its formation sothat he final product maybe separated from the re mixture merely byfiltration: j

The starting material for 0 processes is preferably that prepared byreacting upon a cellulose acetate with a dicarboxylic acid anhydride inthe presence of an organic base such as pyridine as is disclosed andclaimed in our application Serial No. 380,252 referred to above. As waspointed out in that application, the final product of thatesterification is preferably treated with an acid to remove the organicbase therefrom prior to its neutralization with the aqueous hydroxidesolution. If desired, the product resulting from the treatment ofcellulose with the dicarboxylic acid anhydride and an organicbase may beemployed. The acetate-dicarboxylate, however, is preferred as thestarting material. For example, cellulose acetate-phthalate or cellulose.acetate-succinate are eminenty suited for use in this connection.

material The following examples illustrate the embodi: ment of ourinvention in processes in which cellulose acetate-phthalate is used asthe starting Example I 5 100 grams of a' cellulose acetate phthalatehaving a phthalyl content of 35% was dissolved in a liter of anhydrousacetone. A current of dry ammonia gas was then slowly led into thesolution accompanied by constant stirring. As the ammonia was beingintroduced, the ammonium salt of cellulose acetate phthalate wasprecipitated and after an excessof ammonia had been added,. thecompletely precipitated salt had settled to the bottom. The precipitatedsalt was then filtered ofi, washed withacetone and dried. The freshlyprepared product was readily soluble in water and methyl alcohol.

,A kilogram of a cellulose acetate phthalate having a phthalyl contentof about 35% was dissolved in about 10 liters of ethylene glycolmonomethyl ether. A 10% solution'of potassium hydroxide in a mixture ofequal volumes of water 25 and ethylene glycol monomethyl ether was addedslowly and with continuous stirring until the solution was exactlyneutral to both litmusand phenolphthalein. The cellulose acetatepotassium phthalate formed was precipitated out from the mass by pouringit into an excess of acetone. It was then washed several times withacetone and dried. The product was soluble in distilled water,

ethylene glycol monomethyl ether and in various acetone-methyl alcoholmixtures. 5

Example? III The procedure of Example II was repeated except that sodiumhydroxide instead of potassium hydroxide was employed. A product solublein water, ethylene glycol monomethyl ether and in acetone-methyl alcoholmixtures, was obtained.

Sodium'or potassium salts of cellulose acetate phthalate having a lowphthalyl content are also soluble in methyl alcohol, ethyl lactate,benzenemethanol, toluene-methanol and p-methoxy ethyl alcohol. 7

These salts of the cellulosesacetate dicarboxylates solubzl? in suitablesolvents may be coated out into .clea transparent, sheets or skins. For0 example, 0 lulose acetate potassium phthalate may be coated fromwater, aqueous methyl alcohol; acetone-methyl alcohol or ethylene glycolmonomethyl ether.

As compounds which co taln chemically com- 'E'rample II 1 i binedcellulose and yet which are water soluble are rare the alkali metalsalts of the cellulose acetate dicarboxylates give promise of greatutility in the future. They may, for example, find use in adhesivecompositions, as a sizing material or as avehicle for carrying dyes orpigments. Various uses will suggest themselves to individuals in artswhich require a material having the chemical composition and propertiesof the f compounds which we have discovered.

The compounds which we have discovered may be represented by theformula:

represents the Ca portion of a cellulose molecule, X may representeither an acetyl, hydroxyl and/or a -;YM group, Y represents adicarboxylic acid group such as a phthalyl or succinyl group and Mrepresents either NH4, Na, K, Li, Rb or C5." For example, the sodiumsalt of a cellulose acetate phthalate might be represented by theformula,

--OAc t ill O-C ONa a potassium salt of a cellulose acetate succinatemight be represented by the formula and a sodium salt of cellulosediphthalate might be represented by the formula 'JiQiaN. le g cificationand claims in referring to the structural formula of a compound, thatstructural formula, especially where cellulose compounds are involved,does not restrict the compound which it represents to the proportionswhich are set forth therein. For instance, cellulose is represented bymerely a C6 portion of the cellulose molecule. However, due. to thegreat number of these units which are present in cellulose it may bereadily seen that almost anyproportion of groups might be present in acellulose compound.

Having now described our invention, what we claim and desire to besecured by Letters Patent of the United States is: I 1. A salt of acellulose ester represented by the formula,

formula PX in which in which represents a. Ca portion of a cellulosemolecule,

each X represents an acetyl or a .O E Q E-OM group dicarboxylate thecarboxyl groups of the dicarboxylic acid radical being linked byintervening atoms.

5. An alkali metal salt of a cellulose acetate phthalate.

6. An alkali metal salt of a, cellulose acetate succinate.

7. A sodium salt of a cellulose ester containing a dicarboxylic acidradical the carboxyl groups of which are linked by intervening atoms oneof the two carboxyl groups of the dicarboxylic acid radicals beingjoined to the cellulose.

8. A sodium salt of a cellulose acetate dicarboxylate the carboxylgroups of the dicarboxylic acid radical being linked by'interveningatoms.

9. A sodium salt of a cellulose acetate phthalate.

10. A sodium salt of a cellulose acetat-succinate.

11. A potassium salt of a cellulose acetate phthalate.

12. The process of preparing a. water-soluble salt of a dicarboxylicacid ester of cellulose, the carboxyl groups of the dicarboxylic acidradicals thereof being linked by intervening atoms which comprisesslowly reacting upon the est r with an inorganic water-soluble base.

13. The process of preparing a water-soluble salt of a dicarboxylic acidester of cellulose, the

aocaccs carbonyl groups of the dicarborzylic acid radicals thereof beinglinked by intervening atoms which v comprises slowly reacting upon theester with an aqueous solution of a basic alkali metal com.- pound.

ldfilhe process of preparing a water-soluble salt of a dicarboxylic acidester of cellulose acetats,- the carbonyl groups of the dicarboxylicacid radicals being linked by intervening atoms which comprises slowlyreacting upon the ester with an aqueous solution of an inorganicwater-soluble basic compound.

15. The process of preparing a water-soluble. salt of a phthalate acidester of cellulose which salt of a dicarboxylic acid ester of cellulose,the

carbonyl groups of the dicarboxylic acid radicals thereof being linkedby intervening atoms which-comprises slowly reacting upon the ester withan aqueous solution of an alkali metal hydroxide.

18. The process of preparing a water-soluble salt of a phthalate acidester of cellulose which comprises slowly reacting upon the ester withan aqueous solution of an alkali metal hydroxide.

19. The process of preparing a water=soluble salt of a succinic acidester of cellulose which comprises slowly reacting upon the ester withan aqueous solution of an inorganic water-soluble basic compound.

20. The process of preparing a water-soluble salt of a phthalate acidester of cellulose acetate which comprises slowly reacting upon theester with an aqueous solution of an alkali metal hydroxide.

.21. The process of preparing-a water-soluble salt of a succinic acidester of cellulose acetate which comprises slowly reacting upon theester with an aqueous solution of an. alkali metal hy" droxide.

22. The process of preparing a water-soluble salt or an aciddicarboxvlic acid ester of cellulose which comprises slowly reactingupon that ester with an aqueous solution of a water-soluble basic alkalimetal compound.

